Egyptian security forces stand guard after multiple explosions hit the area outside the main campus of Cairo University, in Giza, Egypt, on April 2, 2014. / Amru Taha, AP

by Sarah Lynch, Special for USA TODAY

by Sarah Lynch, Special for USA TODAY

CAIRO â?? Three bombs blasts struck security forces outside Cairo University on Wednesday, killing at least two people as violence in the country persists ahead of an upcoming presidential election.

A police investigations chief was killed and several people were wounded when a twin attack hit a roadside outside the university, located in Giza, the state news agency MENA reported. A third explosion followed, causing no casualties.

The blasts appeared to target riot police who were stationed outside the university to deal with almost-daily student protests against Egypt's current leaders and in support of ousted Islamist leader and Muslim Brotherhood figure Mohamed Morsi.

Following the attacks, Students against the Coup, which often plans and leads university protests nationwide, called off a demonstration planned for noon Wednesday at Cairo University. It denounced the violence and said it is committed to peaceful acts of opposition.

It was unclear who carried out Wednesday's attacks. But they were not a surprise in light of Abdel Fattah Al-Sisi's recent announcement that he will run for president in May elections, said Mustapha Al Sayyid, a political science professor at the American University in Cairo.

Anger and violence aimed at authorities spiked since al-Sisi ousted Islamist leader Mohamed Morsi last July and interim authorities launched a violent crackdown on Islamists and other opposition.

"These acts will continue and this was expected," said Al Sayyid, who also teaches at Cairo University but was not there at the time of the attacks. "This will continue throughout the period of preparation for elections, and if Sisi wins â?? as is expected â?? I think this will continue after his election."

The Sinai-based Ansar Beit al-Maqdis, an Al Qaeda-inspired group, has claimed responsibly for most of the recent deadly attacks, including a string of four bombs blasts that rocked the capital earlier this year, an attack on the interior minister last summer and a February attack on a tourist bus in the Sinai Peninsula.

In response to Wednesday's blasts, security was heightened at Cairo International Airport, the state news agency said.

Over the weekend, the State Department warned U.S. citizens that al-Sisi's presidential candidacy could impact security in Egypt.

"U.S. citizens should closely monitor events and scrutinize their movements closely through the week ending April 6th," a security message said. "Special attention should be paid to places where crowds gather, such as malls, restaurants, and shopping areas."

The State Department also advised Americans to avoid protests, "as firearms have been used by and against protestors," the security message said.